Subaru 20.5HP in BigFoot or Vanguard

[Rickb]

I would really appreciate some input on the feasibility of putting a 20.5 HP Subaru in a Bigfoot(2000) or Vanguard(1998). I will move forward with this swap if I can confirm the following:

1. Use stock clutches;
2. No major retrofits required (I am not a mechanic);
3. No major Electrical; and
4. No major engine mounting fabrication required.

The Bigfoot has an 18HP Briggs and the Vanguard has a 16HP Briggs.

In particular, I am concerned about the following, however would appreciate any other information that I need to make my decision to proceed with the engine swap:

Subaru - EFI - 20.5HP - Any issues with Engine Size and mounting into the engine compartment

Displacement 653 cc

Torque 32.7 ft-lb

Max. Speed 3,600 RPM

Shaft Diameter 1 in. - I believe this is the same for both Briggs
Shaft Rotation CCW - I assume this is the same as the Briggs?
Shaft Length 2.9 in. - Will this match - any issues with the Clutches? - Can I use stock clutches and belt??

Shaft End Tapped (Diameter (in) / Threads Per Inch) 3/8 in. - 24 UNF - Not sure what this is??

Air Cleaner Type Dual element

Fuel Type Gasoline

Fuel Filter No

Oil Capacity 1.5 qt.

Lubrication System Pressure

Low Oil Alert Yes

Low Oil Shutdown Yes

Start Type 12V DC

Ignition System Electronic

Governer System Mechanical

Number of Cylinders 2
Bore Diameter 3.15 in.
Stroke 2.56 in.
Compression Ratio 8.3:1
Muffler No - Can I use the stock???
Spark Plug Use item # 4780112

Any issues hooking up throttle controls??

Any concerns with overheating??....I understand this was a concern with new B&S 23HP??

Thanks, Rick

[Nubs]

If Your not into fabbin' brackets and welding exhaust systems etc I would just go with the 23 Vanguard and be done with it. its the same money in the end.

[Rickb]

Thanks Nubs.....I just heard that there are many problems with the 23HP Briggs (mainly overheating issues) and it would be nice to have the EFI.

Rick

[Nubs]

I've heard that

[Rickb]

Anyone else got any feedback on this??

I know that there are others that installed Subaru motors into Argos.

Will the shaft accept my stock clutch and is the length ok?

Do I need to fab a custom motor mount bracket, or will it bolt into the current config?

Would really appreciate any information out there on this motor install.

Thanks, Rick

[Nubs]

The drive clutch will fit but its just not going to drop in and u'll be driving. Throttle, mounts, wiring, exhaust and fuel lines will all need work. Hard to tell someone if its right thing to do when they have little idea of the skill level of the installer

[Rickb]

Thanks Nubs.....I can handle throttle, wiring, and exhaust mods to suit the Subaru.

I was just hoping to get more feedback on the other major items like shaft length, engine mounts, space in the tub, etc...

Rick

[Rickb]

Thanks Nubs.....I can handle throttle, wiring, and exhaust mods to suit the Subaru.

I was just hoping to get more feedback on the other major items like shaft length, engine mounts, space in the tub, etc...

Rick

Hello, anyone out there put a 20.5 Subaru in a Bigoot/Vanguard?? would really appreciate feedback on this...thanks.

[ARGOJIM]

I'm sure there are Subaru's in Argos somewhere though I've not seen it. Shaft size is fine, physical size should fit in the hole.

Now, you will have to compare shaft heights from the base plate as whether you'll need to adapt the engine to the powerpack frame. Take a center line measurement now and right it down. Oil cooler if so equipped will have to be clearance considered if it is trans side aswell as overall lower and upper widths of engine. Bolt pattern (Crankshaft pto end )to crankshaft inner lip ( where clutch rests) will need to be considered.
You will need some wiring adjustments for sure to adapt from the Subaru harness to the existing main harness.
You will need to hook up an electric fuel pump and possibly a return if the Subaru needs it.
The exhaust will need modification for certain.
You may need to adapt the cool air intake.
Overall engine height at top of air cleaner needs to be considered to run with a hood on.


Here is a pic I found of a Predator in a Response ( same body/hood style) notice air cleaner is no longer mounted.
These pics show muffler will distort the body as shown.

[Rickb]

Thanks for the prompt response ARGOJIM...great advice.

I feel good about doing most of the mods that you mentioned...except for the following:

1. Remote throttle controls....subaru does not seem to have a similar set-up to ARGO...could I use B&S ARGO controls?;
2. Dimensions (Horiz/vert) between the Driven Clutch and the Driver.....is there some flexibility here or do they need to be bang on??

[ARGOJIM]

Subaru's site has the specs on the engine, check the widths as it looks wide. I just don't like the oil filter placement as it may interference with the brake duct. There is a manual you could download for throttle controls.

[Rickb]

Hi ARGOJIM,

The Predator engine install pictures that you provided looks very similar to the Subaru/Robin Engine install that I am planning. Do you have more pictures that show the exhaust details?? My muffler looks just like the one in the photo, and it will end up in a similar location. I wonder if this will cause excessive heat into the tub, and/or melt the hood plastics??? I also would like to know where the exhaust tail pipe routes to the exterior in this set-up?

[ARGOJIM]

Rick,
that picture was a web find of a predator in a Response 8x8 which has the same nose configuration as your machine and was a 18hp vanguard. That picture shown I'd be concerned with body heat, if it were me I'd do something different with the exhaust preferably using a set up like you have now either fabbed by you or a local welder.

Again I would check all clearances, though as Zuk wrote anything can be fabbed to make it work for proper spacing and alignment. I do have pictures in my gallery of "Phil, the bastard " which is a Conquest powered by a Predator with some pictures to reference. NOTE; the Conquest has a higher nose/hood configuration so take that into account, but it will give you the general idea of what was done. I would have changed the exhaust had I still had it, but it worked with all the shielding.